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CNN Reports FEDEX crash in Tokyo

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CNN Reports FEDEX crash in Tokyo

Old 24th Mar 2009, 08:11
  #181 (permalink)  
 
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Touch'n' oops,

Thanks for correcting me but I said hubs not rims. The hubs can clearly be seen along with tie bolts. The majority of the wheels are still bolted to the axle. Thanks for the photo, but I'm fully aware of what a DC-10/MD-11 nose tyre/wheel assy looks like thanks.
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Old 24th Mar 2009, 10:37
  #182 (permalink)  
 
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I'm wondering how this impact compares with some other landing accidents. Someone mentioned the Iberia 340 at Quito(?) being 3g, but I would have thought the 777 at LHR would have been heavier, and possibly the Britannia in Girona. In the 777 case, one landing gear separated and the other went through the top of the wing - a much better outcome than the wing coming off and the aircraft rolling inverted. The Ryanair 737 in Ciampino also had the u/c partly go through the top of the wing.

Retraso.com, accidentes aereos, air disasters, air crashes,

Aircrew Buzz: Ryanair Flight FR4102 Emergency at Rome-Ciampino: Multiple Bird Strikes

In the Brittania case:
"The aircraft, yawed considerably to the right of its direction of travel, then passed through the fence, re-landed in a field and both main landing gears collapsed.

It came to rest after a 244 metre slide across the field, with the fuselage almost structurally severed at two points, the NLG and both engines detached and the underside of the left wing torque box split open near the wing root. The three fuselage parts remained upright, connected by cables, wires and other services, but rolled to the left between 8-16°. There was no fire".

Just because the MD11 is certified to a certain structural limit (Xg) doesn't mean the wing should fall off when that structural limit gets to
X.1g!

Last edited by Propellerhead; 24th Mar 2009 at 10:55.
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Old 24th Mar 2009, 11:01
  #183 (permalink)  
 
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I have a gut feeling that this MD11 experienced more than 3 G's....more than the quito Airbus.

Of course I'm patiently waiting for the final report, just like everyone else. But since someone mentioned pilot induced occilation, check this out:


YouTube - Crazy landing with L-410

It shows what can happen with PIO.
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Old 24th Mar 2009, 11:11
  #184 (permalink)  
 
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Someone mentioned the Iberia 340 at Quito(?) being 3g
Landing limits are more generally expressed as a rate-of-descent e.g. 10 ~ 15 ft/s max (and at given landing weights)...

The 'G' that something experiences, will vary across the whole aircraft structure, and parts thereof, depending on it's mass, stiffness, interconnectedness and instantaneous crash dynamics.

For instance, the recent AMS 737 accident, it is quite evident that the forward fuselage experienced many times the 'g' force of the centre fuselage and wing section.

Ultimately it's the forces that count, which are dependent upon the mass of the part that's accelerated, which (mass) could of course change dramatically during the course of an accident... so any comments on what should and shouldn't break and how, is highly speculative. Granted though, that MD-10 & 11s seem to come apart pretty dramatically in such incidents... it would have been the accelarative forces of the flipping of the right wing, that seemed to break it outboard of the pylon.

Last edited by HarryMann; 24th Mar 2009 at 11:21.
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Old 24th Mar 2009, 12:24
  #185 (permalink)  
 
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Intresting reviews on md-11

website where this was published:

That Tragic MD-11 Safety Record


Subject: WSJ
/Jet's Troubled History/continued
Yet sometimes, at low altitude, the opposite occurs: Pilots tell of pulling with all their might and finding the plane hardly responded. That can be a problem during landing. In several instances where pilots brought down their MD-11s too rapidly and tried to compensate at the last minute, they smacked the aircraft's tail on the runway or caused other damage.
That's what NTSB investigators reckoned took place in 1997 when FedEx pilots tried to land an MD-11 at Newark. The plane touched down too hard, bounced, rolled right, broke its right wing, flipped over and was destroyed by fire. The two pilots, who escaped, took most of the blame. But the safety board also raised questions about the plane's "stability and control characteristics," the design of its landing gear and why its wing broke off, a rare occurrence in similar hard-landing accidents.
Boeing acknowledges the tail-strike problem but says it has addressed the matter in a variety of ways, including new software and better pilot-training programs. It says there hasn't been a serious MD-11 tail strike reported in the past year or so.
'Just Quit Flying' Veteran FedEx captain Jack Burke, who once walked away from an MD-11 tail strike, has described his caution about flying the plane. "The first 100 feet and the last 100 feet are where the crew really has to sweat it," he says. If the descent isn't exactly right, Capt. Burke adds, he will abort the landing, because "the plane can just quit flying on you. There is simply no time to recover."
Some pilots, reflecting the joking camaraderie of their ranks, have adopted macabre nicknames for the MD-11. "Death Star," some facetiously call it, according to the Air Line Pilots Association's safety-committee chairman. Others call it the Scud, after Iraq's unpredictable Gulf War missile.
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Old 24th Mar 2009, 13:35
  #186 (permalink)  
 
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From the stand point of a casual observer;

Could the violent up-down movement seen on the video have been caused by freight breaking loose after initial heavy impact? in my mind, freight shoving backwards, then forwards, then all over the shop would be enough to cause all sorts of weight distribution/CofG problems?

go easy - I'm still learning
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Old 24th Mar 2009, 13:40
  #187 (permalink)  
 
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Design Question

Can anyone please point to any documented design parameters for subsequent aircraft models (be it Brand A or Brand B) which have specifically taken into account the need to avoid the situation displayed by this accident? Namely those which take into account the previously-known handling characteristics of an MD-11 in particular (especially as a cited justification? - eg "touchy/sensitive" elevator control leading to new design feature as follows, ..., bearing in mind MD-11 behavour X/Y/Z)?

Put another way, are there any formally-documented design criteria post the 1970s/80s which point to a subsequent overall aircraft design feature which particularly avoids the "known" handling issues of an MD-11 (eg that which has apparently led to the accident in NRT)? I accept the -10 to -11 changes in design but seek information about other manufacturers takng certain things into account.

Also, I'm not a "legal eagle", just curious about whether "known" handling difficulties in one type have been acknowledged/rectified in subsequent airframe designs by other manufacturers.
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Old 24th Mar 2009, 14:11
  #188 (permalink)  
 
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Looking at this video (there are more than one),

BBC NEWS | World | Asia-Pacific | Fiery Tokyo plane crash kills two

if you quickly stop/start the video between 4s and 5s in then the starboard wing seems to be swept back at a massive angle at one point
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Old 24th Mar 2009, 15:15
  #189 (permalink)  
 
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Just because the MD11 is certified to a certain structural limit (Xg) doesn't mean the wing should fall off when that structural limit gets to
X.1g!
***************

actually it can withstand abt 3x its certified limit.
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Old 24th Mar 2009, 15:48
  #190 (permalink)  
 
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The above referenced BBC link states that this was the first fatal accident in the history of NRT which opened back in 1978. If true, then that is an impressive stat all by itself!
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Old 24th Mar 2009, 16:00
  #191 (permalink)  
 
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This is very pertinent. Boeing designs its landing gear to shear off under excessive vertical loads; this is far safer than having it break the wing spar, as apparently happens on the MD-11. I think this goes back to when McDonnell took over Douglas; McDonnell had never designed anything except military planes, and if they met specifications then everyone was happy. Boeing, Douglas, and Lockheed, however, had learned that when designing airliners you made it as safe as you could, period. The regulations were regarded as just the starting point. I am convinced that many of the problems with the DC-10/MD-11 come from the fact that the military people at McDonnell were in control of the company, and the Douglas people who really knew how to build an airliner were not listened to.
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Old 24th Mar 2009, 16:16
  #192 (permalink)  
 
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SEPilot,

That occurred to me many years ago after discussing handling probs and the small tailplane with an AA "Scud" driver.

Douglas pretty much bankrupted itself into the hands of McDonnell by building tough airframes. When the St Louis outfit took over the financial reins, its first civil creation, the DC10, was pretty much a General Dynamics fuselage mated to a Douglas wing - primarily because DC9 demand was putting a strain on the Long Beach facilities and it was more cost effective to build the fuselage elsewhere.

The over large tailplane of the DC10 was a cheaper alternative than an active de-icing system and the MD-11 contains hall marks of fighter thinking in its wing position, the redesign of the tailplane and many of the handling features.

I've yet to meet anyone in engineering or who flies the MD-11 with anything really good to say about it.
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Old 24th Mar 2009, 16:18
  #193 (permalink)  
 
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Can anyone post the decision logic of the LSAS system? I can discern some of it from the FCOM discription, but not all of it. Anytime automation is "in the loop" at the time of an accident, I think it's worth looking at.
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Old 24th Mar 2009, 16:27
  #194 (permalink)  
 
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What is the max certified g limit - 2.5g? I can't see that landing being more than 7.5g. I agree with the previous poster's comments about g force varying throughout the structure.
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Old 24th Mar 2009, 16:35
  #195 (permalink)  
 
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Just because the MD11 is certified to a certain structural limit (Xg) doesn't mean the wing should fall off when that structural limit gets to
X.1g!
***************

actually it can withstand abt 3x its certified limit.
Hmm... I hope you don't fly to such limits.

FAR25 says:

"Sec. 25.303 Factor of safety.

Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified."


Please have a look at the youtube video of the B777 wing load test. It breaks at 154% limit load, proving designers don't put in more strength (and weight) than necessary.
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Old 24th Mar 2009, 16:40
  #196 (permalink)  
 
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I think Harrymann may be on to something.

First we have from the FCOM
During take-off and landing flight phases, when (LSAS) PAP or PNL is active, approximately 10-15 pounds of force on the control column is required to override LSAS.
Then we have:
Bounced Landing Recovery
If the aircraft should bounce, hold or re-establish a normal landing attitude and add thrust as necessary to control the rate of descent. Avoid rapid pitch rates in establishing a normal landing attitude.
CAUTION: Tail strikes or nosewheel structural damage can occur if large forward or aft control column movements are made prior to touchdown.
So, we need 10-15 pounds of control column "break out force" to override the LSAS PAP or PNL active modes below 100ft RA, when light pitch rates are needed, in an aircraft that already has low pitch stability.

What am I missing here?
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Old 24th Mar 2009, 16:42
  #197 (permalink)  
 
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Meaningless

“The above referenced BBC link states that this was the first fatal accident in the history of NRT which opened back in 1978. If true, then that is an impressive stat all by itself!”

If you’re an ‘American Football’ or ‘Baseball/Basketball’ fan, then yes I can see how you’re impressed by a meaningless statistic!
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Old 24th Mar 2009, 16:54
  #198 (permalink)  
 
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What is the max certified g limit - 2.5g? I can't see that landing being more than 7.5g. I agree with the previous poster's comments about g force varying throughout the structure.
Please...
The airworthiness requirements, FAR 25 for transport category airplanes, are all on the web. Here is a link and here's the basic requirement for the landing gear.

"Sec. 25.473 Landing load conditions and assumptions.

(a) For the landing conditions specified in Sec. 25.479 to Sec. 25.485 the airplane is assumed to contact the ground--
(1) In the attitudes defined in Sec. 25.479 and Sec. 25.481;
(2) With a limit descent velocity of 10 fps at the design landing weight (the maximum weight for landing conditions at maximum descent velocity); and <....>"

So the gear must withstand a 600 fpm descent rate as the service limit load, and in the certification tests it must pass one test at ultimate loads corresponding to 900 fpm. Note also that there are a number of conditions attached to those requirements, in reality it's not just that simple number.
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Old 24th Mar 2009, 17:18
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The certification requirements dictate what loads the landing gear must take, they do not dictate what happens when they are exceeded. This is where real design takes place; to make sure that when it fails it does so in the most benign fashion possible. In this case it would be that the landing gear shear off, but with the MD-11 it appears that it tends to break the wing spar. Note the BA 777 at Heathrow; had it been built like the MD-11 and the wing spar had broken instead of the landing gear going through the wing that one might well have ended up on its back as well, and in that case it is highly likely that there would have been fatalities. If the gear would have detached in the same manner perhaps none of the three MD-11's that flipped on landing would have done so.
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Old 24th Mar 2009, 17:35
  #200 (permalink)  
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I have plenty of good to say about the MD11.

But it is not proper right now. Two of my coworkers are dead.

We'll discuss it later.
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